Preheat the oven to 375°F (190°C).

In a mixing bowl, whisk together 2 cups gluten-free all-purpose flour, 1 tablespoon sugar, 1 teaspoon salt, and 1 tablespoon baking powder until evenly combined.

In a separate bowl, mix 1 cup warm water, 2 tablespoons olive oil, and 1 teaspoon apple cider vinegar.

Pour the wet ingredients into the dry ingredients and stir with a rubber spatula until no dry spots remain.

If using flaxseed meal, fold in 1/4 cup flaxseed meal into the batter.

Grease a 9×5-inch loaf pan with oil or line with parchment paper.

Transfer the batter into the prepared loaf pan and smooth the top.

Bake for 45 minutes at 375°F (190°C), or until the top is golden brown and a toothpick inserted into the center comes out clean.

Let the bread cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before slicing.